Actually apply the pre-commit fixers to the codebase.

This can be redone manually with
`pre-commit run --all`

While the pre-commit hook could be merged to run locally,
it is much cleaner to align all the files to best-practice
syntax in a single commit. It is also required for server-side
validation.

util/batching_queue_test.go

@@ -1,12 +1,13 @@
 package util_test
 
 import (
-	"github.com/stretchr/testify/require"
-	"heckel.io/ntfy/util"
 	"math/rand"
 	"sync"
 	"testing"
 	"time"
+
+	"github.com/stretchr/testify/require"
+	"heckel.io/ntfy/util"
 )
 
 func TestBatchingQueue_InfTimeout(t *testing.T) {

util/content_type_writer_test.go

@@ -2,9 +2,10 @@ package util
 
 import (
 	"crypto/rand"
-	"github.com/stretchr/testify/require"
 	"net/http/httptest"
 	"testing"
+
+	"github.com/stretchr/testify/require"
 )
 
 func TestSniffWriter_WriteHTML(t *testing.T) {

util/embedfs_test.go

@@ -2,11 +2,12 @@ package util
 
 import (
 	"embed"
-	"github.com/stretchr/testify/require"
 	"net/http"
 	"net/http/httptest"
 	"testing"
 	"time"
+
+	"github.com/stretchr/testify/require"
 )
 
 var (

util/gzip_handler_test.go

@@ -2,11 +2,12 @@ package util
 
 import (
 	"compress/gzip"
-	"github.com/stretchr/testify/require"
 	"io"
 	"net/http"
 	"net/http/httptest"
 	"testing"
+
+	"github.com/stretchr/testify/require"
 )
 
 func TestGzipHandler(t *testing.T) {

util/limit.go

@@ -2,10 +2,11 @@ package util
 
 import (
 	"errors"
-	"golang.org/x/time/rate"
 	"io"
 	"sync"
 	"time"
+
+	"golang.org/x/time/rate"
 )
 
 // ErrLimitReached is the error returned by the Limiter and LimitWriter when the predefined limit has been reached

util/limit_test.go

@@ -2,9 +2,10 @@ package util
 
 import (
 	"bytes"
-	"github.com/stretchr/testify/require"
 	"testing"
 	"time"
+
+	"github.com/stretchr/testify/require"
 )
 
 func TestFixedLimiter_Add(t *testing.T) {

util/peek_test.go

@@ -1,10 +1,11 @@
 package util
 
 import (
-	"github.com/stretchr/testify/require"
 	"io"
 	"strings"
 	"testing"
+
+	"github.com/stretchr/testify/require"
 )
 
 func TestPeak_LimitReached(t *testing.T) {

util/time.go

@@ -2,11 +2,12 @@ package util
 
 import (
 	"errors"
-	"github.com/olebedev/when"
 	"regexp"
 	"strconv"
 	"strings"
 	"time"
+
+	"github.com/olebedev/when"
 )
 
 var (

util/time_test.go

@@ -1,9 +1,10 @@
 package util
 
 import (
-	"github.com/stretchr/testify/require"
 	"testing"
 	"time"
+
+	"github.com/stretchr/testify/require"
 )
 
 var (